Optically sensitized photographic emulsion



Patented Aug. 3, 1954 UNITED STATES ATENT OFFICE OPTICALLY SENSITIZED PHOTOGRAPHIC EMULSION Frank Peter Doyle and Harry Derek Edwards,

Barnet, England, assignors, by mesne assignments, to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application October 5, 1951, Serial No. 250,022

6 Claims.

X is oxygen or sulphur;

X is sulphur or =NR (R being hydrogen or an organic group such as alkyl or aryl) and R is hydrogen or alkyl.

Particular combinations of substituents in the terminal grouping which have shown satisfactory results when tested are as follows:

(a) X is sulphur, R is ethyl and X is =NCsH5 or =NCH3 or sulphur.

(b) X is oxygen, R is ethyl and X is sulphur.

(e) X is oxygen, R is hydrogen and X is sulphur.

The new sensitizing dyestuffs may be prepared by reacting a compound of the formula:

chi-x oo- -c\ N ooon (I) wherein X X and R are as already identified, with a cyanine type dyestuif intermediate containing a group reactive with the ='CHz group of the said compound.

Preferably the cyanine type dyestufl intermediate has one or other of the following formulae:

wherein Z is the residue of a heterocyclic nucleus; R is alkyl;

2 R and R' are either the same or diiferent and are alkyl;

X is an anion;

Y is a reactive group such as alkylmercapto,

acetanilido, or a halogen; and

n is either zero or an integer.

The nature of the reaction is exemplified by the following illustrations:

C COOR HX HY Compounds of Formula I may he prepared in a variety of ways. For instance, the compound 3-carbethoxy-3-cyano-4-keto-2-phenylimino tetrahydrothiophene, of the formula:

U can be prepared by the following reactions (see Ruhemann, J. Chem. $00., vol. 93, page 626):

CH2 PhNCS COOEt /C=NP11 CHy-S HG ClCH2.COOEt C=NPh CN COOEt CO'C (G1CH2.COOH) ON COOEt CHz-O :5 COC CN COOEt (VII) has been prepared in accordance with the following procedure:

12 parts potassium hydroxide were dissolved in 30 parts water and 5.4 parts of ethyl cyanacetate were added. The solution, which had become warm, was cooled to room temperature and 10.3 parts of xanthodiacetic acid monoamide were added. The resulting solution was allowed to stand overnight and was then acidified with dilute sulphuric acid and warmed gently on awater bath for 30 minutes. The solution was cooled and the reddish brown precipitate was filtered. The product was found to be unstable and crystallisable only with difiiculty, and was therefore used in its crude form.

Another preparation, which is believed to produce 3 carboxy-3-cyano-4-keto-2-thiotetrahydrofurane, was conducted as follows.

18 parts potassium hydroxide were dissolved in 30 parts water and to the cooled solution was added 6.4 parts cyanacetic acid. The solution was re-cooled and parts of Xanthodiacetic acid monoamide were added and the solution allowed to stand overnight. The solution was then acidified with dilute sulphuric acid, and warmed on a water bath for minutes. On cooling, the product precipitated and on filtration a fawn coloured solid was obtained which was used without further purification.

A further compound of Formula I, namely 3- carbethoxy 3 cyano-4-keto-2-thiotetrahydrothiophene, of the formula:

cups

ON 0 o OEt VIII has been prepared in accordance with the following procedure:

Stage 1.Dip0tassiwm p cycmo ,6 carbethozc-y c: dimercapto ethylene again evolved and the suspended solid passed into the solution which had become bright yellow. A heavy precipitate of a yellow solid quickly appeared, and after allowing the solution to stand 1 hour was filtered and washed with alcohol and ether. The yield was 75% of theoretical.

When a similar procedure was carried out using caustic soda or sodium metal in place of potassium hydroxide, the disodium salt was formed in solution and did not precipitate. The solution of this disodium salt could be used for the following preparation but it is not so convenient as using the isolated dipotassium salt.

The dipotassium salt could also be prepared by using potassium metal dissolved in alcohol in place .of the potassium hydroxide.

Stage 2 4 parts chloracetic acid were dissolved in 25 cos. water, and neutralised carefully with solid anhydrous sodium carbonate. 10 parts of dipotassium p-cyano-fi carbethoxy e-dimercapto ethylene were added, and the resulting solution was heated for half an hour on a water bath. Alternatively the solution could be stood overnight at room temperature. Dilute sulphuric acid was then added to precipitate the product, which was filtered, washed with water, and dried, when it was obtained as a fawn powder, M. Pt. C.

The product may be purified by dissolving in acetone and reprecipitatingwith water. The M. Pt. is raised by this purification to 134 C.

As mentioned above, the disodium salt of 5 cyano ,8 carbethoxy a dimercapto ethylene can he used for this preparation.

A typical compound of Formula II is:

This is a Well known dyestufi intermediate. A suitable compound of Formula III is dimethylamino benzaldehyde.

The following examples illustrate the invention:

EXAMPLE 1 2(3 ethyl benethiaeole) 5 -(3 cm'bethorcy 3- cycmo 4 keto 2 phenylz'mz'no tetrahydrothiophen'e) dimethine meroc'janine 1.5 parts 3-carbethoxy-3-cyano-4-keto-2-phenylimina-tetrahydrothiophene (prepared as mentioned above in respect of Formula VI), 2.2 parts Z-beta-acZet-anilidovinyl benzthiazole ethiodide (Formula IX) and 30 parts of pyridine were heated under reflux for 1 hour. The red solution obtained was then poured into 30 parts of water and cooled, when the dyestuff crystallised. This was removed by filtration, washed and crystallised from benzene. M. Pt. 301-2 C.

This dyestufi when incorporated in a gelatine silver iodo bromide emulsion extended the sensitivity to 6506 A with a maximum at 5700 A.

5 EXAMPLE II 2(3 ethyl thiazoline) 5 (3 carbethoxy 3- cycmo 4 keto 2 phenylimino tetrahydrothz'ophene) dimethine merocyanine EXAMPLE III 2 (If-ethyl 5-methyl benzomazole) -5- (3-ca1'bethcry-3 cyano-4 Iceto-2-phenyZimino-tetmhydrothiophene) dimethz'ne merocyamne C O OEt (XII) 1.5 parts 3-carbethoxy-3-cyano-4 keto-2- phenyliminotetrahydrothiophene, 2.2 parts 2 beta acet anilidovinyl 5 methyl benzoxazole ethiodide and parts of pyridine were heated under reflux for 1 hour. The orange solution obtained was poured into water, and the dystufi was isolated as in Example I. M. Pt. 311 C.

This dyestufi when incorporated in a gelatine silver iodo bromide emulsion extended the sensitivity to 5,500 A with a maximum at 5,300 A".

EXAMPLE IV 2 3-methyl-S-phenyZ-benzomeole) -5- (S-carbethoxy-3-cyano-4-Iceto Z-phenylimz'no tetrahydrothiophene) dimethine merocyanine 1.5 parts 3-carbethoxy-3-cyano-4-keto 2-phenyliminotetrahydrothiophene, 2.7 parts 2 betaacet-anilidovinyl5-phenyl benaoxazole ethiodide and 30 parts of pyridine were heated under reflux for 1 hour. The dyestuff obtained was isolated as in Example I. M. Pt. 322-3 C.

This dyestuff when incorporated in a gelatine silver iodo bromide emulsion extended the sensitivity to 5,500 with a maximum at 5,300 A.

2(3-ethyl-4:5 naphthoxazole) -5.( 3-carbethozcy scyano 4 Iceto 2 phenylimino tetrahydrothz'ophene) dimethine merocyanine O0 OEt (XIV) 1.5 parts 3-carbethoxy-3-cyano-4-keto-2 phenlyimino-tetrahydrothiophene, 2.7 parts 2-betaacet anilidovinyl 4:5 naphthoxazole etho p-toluene sulphonate and 30 parts pyridine, were heated under reflux for 1 hour. The dyestuff obtained was isolated as in Example I. M. Pt. 354 C.

This dyestuff when incorporated in a gelatine silver iodo bromide emulsion extended the sensitivity to 5,500 A with a maximum at 5300 A".

EXAMPLE VI 2(3 ethyl thz'azoline) 5 (3 carbethomy 3 cyano 4 e keto 2 methylimino tetrahydrothz'ophene) dimethine merocyamne 1.5 parts 3-carbethoxy-3-cyano-4-keto-2-methylimino tetrahydrothiophene, 2 parts 2-betaacet anilidovin'yl thiazoline ethiodide and 30 parts of pyridine were heated under reflux for 30 minutes. The dyestuif obtained was isolated as in Example I. M. Pt. 284 C.

This dyestufi when incorporated in a gelatine silver iodo bromide emulsion extended the sensitivity to 5,800 A with a maximum at 5,200 A.

EXAMPLE VII 2 (3 ethyl benzthz'aeole) 5 (3 carbethoxy 3 cycmo 4 keto 2 methg/Zimino tetrahydrothiophene) dimethine merocyanine 1.5 parts 3-carbethoxy-3+cyano-4-keto-2-methyliminotetrahydrothiophene, 2.2 parts 2 betaacet-anilidovinyl ,benzthiazole ethiodide, and 30 parts pyridine were heated under reflux for 1 hour. The dyestufi obtained was isolated as in Example I. M. Pt. 294 C.

This dyestuff whenincorporated in a gelatine silver iodo bromide emulsion extended the sensitivity to 5,900 A with a maximum at 5,700 A.

EXAMPLE VIII 2(3 ethyl benzthz'aeole) 5 (3 car-booty 3 cyano 4 keto 2 thz'o tetrahydrofumne) dimethine merocyanz'ne on ooon xvii 0.85 part 3-carboxy-3-cyano-4-ket0-2-thiotetrahydrofurane (prepared by the preparation described above), 2.0 parts of 2. beta-acet-anilidovinyl benzthiazole ethiodide, and 25 parts of pyridine were heated under reflux for 1 hour. The red solution obtained was poured into water, cooled, and the dyestuff removed by filtration and crystallised from ethylene glycol mono methyl ether to give mauve crystals. M. Pt. 287 C.

The dyestuff when incorporated in a gelatinosilver iodo bromide emulsion, sensitized with a maximum at 5800 A extending to 6050 A".

EXAMPLE IX 2(3 ethyl benzthiazole) 5 (3 carbethoxy 3 cyano 4 keto 2 thiotetrahydrofurane) dimethine merocyanine (XVIII) 0.95 part 3-carbethoxy-3-cyano-l-keto-2-thiotetrahydrofurane (prepared by the preparation described above in respect of Formula VII), 2.0 parts of Z-beta-acet-anilidovinyl benzthiazole ethiodide and 25 parts pyridine were heated under reflux for 1 hour. The dyestufi was isolated as in Example VIII in the form of mauve crystals. M. Pt. 295 C.

The dyestuff when incorporated in a gelatinosilver iodo bromide emulsion sensitized with a maximum at 5800 A extending to 6050 A".

EXAMPLE X 2(3 ethyl thiaeoline) 5 (3 cm'bethowy 3 cyano 4 keto 2 thiotetmhydrothiophene dimethine merocyanine C COOEt (XIX) 0.5 part 3-carbethoxy-3-cyano-4-keto-2-thiotetrahydrothiophene (prepared as described above in respect of Formula VIII), 1.0 part 2 beta-acet-anilidovinyl thiazoline ethiodide and parts of pyridine were refluxed for 1 hour and then poured into water. The solution was cooled and the dyestufi" filtered, washed and re-crystallized from benzene to give crystals. M. Pt. 235-240 C.

EXAMPLE XI 2(3 ethyl benzthiaeole) 5 (3 carbethoxy- 3 cyano 4 keto 2 thiotetmhydrothiophene) dimethine merocyanine co-o ON COOEt 11.

8.4 parts 2 beta-ethylthiovinyl benzthlazole etho-p-toluene sulphonate (prepared and reacted in situ) 4.6 parts 3 carbethoxy 3-cyano-4-keto-2 thiotetrahydrothiophene, and 50 parts pyridine were boiled together under reflux for 1 hour. The red solution was poured into water, cooled, and

the crude dyestufi separated by filtration. This was crystallised from benzene to give a dark brown amorphous powder. M. Pt. 243 C.

The dyestuff when incorporated in a gelatinosilver iodo bromide emulsion sensitized with a maximum at 5,700 A extending to 6,800 A.

EXAMPLE XII 5 [(3 ethyl dihydrobenethiazolylidene (2))] 3 carbethozry 3 cyano 4 keto 2 thictetrahydrothiophene 1.15 part 3 carbethoxy-3-cyano-4-keto-2 thiotetrahydrothiophene, 2.0 parts 2-ethylmercapto benzthiazo'le etho-p-toluene sulphonate, and 60 parts of pyridine were heated under reflux for 1 hour and poured into water. The yellow precipitate was filtered, washed, and recrystallised from benzene, to give fawn-yellow crystals. M. Pt. 283 C.

EXAMPLE XIII 2 (3 ethyl dihydrobenzthiazolylidene (2) 3- carbethoccy 3 cyano 4 lceto 2 phenylimmo-tetrahydrothiophene 0N 000m xxn 0.? part B-carbethoxy-B-cyano-4-keto-2-phenyliminotetrahydrothiophene, 1.0 part 2-ethylmercapto-benzthiazole etho-p-toluene sulphonate, and 30 parts of pyridine, were heated under reflux for 1 hour. The solution, which contained solid dyestufi that had separated during the heating period, was poured into water, and the crude dyestufi removed by filtration. This was crystallised from a large amount of benzene to give yellow crystals. M. Pt. 340 C.

EXAMPLE XIV Z-(S-ethyl benzthiaeole) -5(3 carbethoxy 3-031- ano 4 keto 2 phenyliminotetrahydrothio phene) hearamethine merocyanine 9 EXAMPLE XV ON 000m (XXIV) 0.75 part p-dimethylamino benzaldehyde, 1.15 parts 3-carb,ethoxy-3-cyano-4-keto-2-thio-tetrahydrothiophene, and 30 parts absolute ethyl alcohol, were heated under reflux for 30 minutes. The thick red precipitate was then filtered, washed with alcohol, and recrystallised from benzene, to give red needles. M. Pt. 239 C. It should be noted that it was not found necessary to use a condensing agent in this example since a better yield was obtained without it.

The dyestuff when incorporated in a gelatinosilver iodo bromide emulsion sensitized with a maximum at 4,500 A extending to 5,500 A.

What we claim as our invention and desire to secure by Letters Patent is:

1. A photographic silver halide emulsion containing as a sensitizer a dyestufl? having the formula:

Z is the residue of a heterocyclic nucleus;

R is selected from the group consisting of hydrogen and alkyl;

R is alkyl;

X is selected from the group consisting of oxygen and sulphur;

X is selected from the group consisting of sulphur and NR (where R is itself selected from the group consisting of hydrogen, alkyl, and aryl); and

n is zero or an integer from one to three.

2. A photographic silver halide emulsion containing as a sensitizer a dyestuff having the formula:

g o=o-o C COOCIHB 3. A photographic silver halide emulsion containing as a sensitizer a dyestufi having the formula:

4; A photographic silver halide emulsion con taining as a sensitizer a dyestuff having the formula:

5. A photographic silver halide emulsion containing as a sensitizer a dyestufl having the -o H 2 0(1 ooooln, 6. A photographic silver halide emulsion containing as a sensitizer a dyestufl having the formula:

Chemical Abstracts, 16:3101 (Abstract of Brit. Med. Journal, 1922, I, 514-515).

Chemical Abstracts, 19:530 (Abstract of Proc. Roy. Soc., London, 963, 317-333, 1924). 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION CONTAINING AS A SENSITIZER A DYESTUFF HAVING THE FORMULA: 